Added the ability to explicitly calculate and cache a given range of holidays

[ndbroadbent]

Hi there,

Our app does a lot of date calculations, and we previously had a hard-coded list of holidays. After switching to the holidays gem, we noticed that some of our requests were taking 30% longer because of many holiday calculations.

This pull request adds a simple Hollidays.cache_between method, so that we can calculate and cache a list of holidays when the app boots. For example, I've added this in an initializer:

Holidays.cache_between Time.now, 2.years.from_now, :us, :observed

Please let me know if you think there's a better way to do this.

[hahahana]

Thanks, this looks great. I'll take a look ASAP, hopefully we can get this all gem'd up sometime next week.

[hahahana]

Hi, sorry for the delay, I'm looking at this right now. It'll take a little more time to test it though vs the other pull requests. After going through all the code, I'm a little wary of releasing a gem atm, just because I feel like we are missing a lot of test coverage for the rest of this decade (and have been getting pull requests along the lines of, this definition is wrong/missing, etc.) and I'm thinking about a way to make the data in the base a little more manageable. Basically, right now my main worry is the underlying data itself. But don't worry, I have definitely not forgotten about this part and I really like it a lot.

[ghiculescu]

How does everyone feel about merging this in?

[ppeble]

@ghiculescu This is my next priority. I'll spend some time tonight looking it over. In the meantime, could you merge in the latest master to resolve the conflicts? That way we will have a clean merge.

EDIT: Oops, I realize now that this wasn't yours originally, @ghiculescu. My mistake!

@ndbroadbent I know that it has been a while but would you mind merging in the latest master?

[ghiculescu]

@ptrimble I actually tried merging it against master on my own fork anyway. Seemed to go fine.

TandaHQ@7a0cc60

Do you want me to create a new pull request?

[ppeble]

Sure, that sounds great. I'll close this one once you create the new PR and we'll merge it in.

[ppeble]

Oh, and while we're at it, would you mind adding a small section to the README to show how this functionality is used?

[ghiculescu]

@ptrimble -- see #92

[ppeble]

Here we are! I figured things out and put your names on the commits in a separate PR. Once the builds are green I'll merge them in and our long nightmare will be over. 😉

Thanks for your patience, all! I'm going to close this out in favor of this one: #100

[ppeble]

All done! Thanks again, guys, Release forthcoming.